Heat index and adjusted temperature as surrogates for wet bulb globe temperature to screen for occupational heat stress

Details

• Personal Author:
  Bernard, Thomas E. ; Iheanacho I
• Description:
  Ambient temperature and relative humidity are readily available; and thus tempting metrics for heat stress assessment. Two methods of using air temperature and relative humidity to create an index are Heat Index and Adjusted Temperature. The purposes of this paper were: (1) to examine how well Heat Index and Adjusted Temperature estimated the wet bulb globe temperature (WBGT) index; and (2) to suggest how Heat Index and Adjusted Temperature can be used to screen for heat stress level. Psychrometric relationships were used to estimate values of actual WBGT for conditions of air temperature, relative humidity, and radiant heat at an air speed of 0.5 m/s. A relationship between Heat Index [degrees F] and WBGT [degrees C] was described by WBGT = -0.0034 HI(2) + 0.96 HI - 34. At lower Heat Index values, the equation estimated WBGTs that were +/-2 degrees C-WBGT around the actual value; and to about +/-0.5 degrees C-WBGT for Heat Index values > 100 degrees F. A relationship between Adjusted Temperature [degrees F] and WBGT [degrees C] was described by WBGT = 0.45 Tadj - 16. The actual WBGT was between 1 degrees C-WBGT below the estimated value and 1.4 degrees C-WBGT above. That is, there was a slight bias toward overestimating WBGT from Adjusted Temperature. Heat stress screening tables were constructed for metabolic rates of 180, 300, and 450 W. The screening decisions were divided into four categories: (1) < alert limit; (2) < exposure limit; (3) hourly time-weighted averages of work and recovery; and (4) a Caution zone for an exposure > exposure limit at rest. The authors do not recommend using Heat Index or Adjusted Temperature instead of WBGT, but they may be used to screen for circumstances when a more detailed analysis using WBGT is appropriate. A particular weakness is accounting for radiant heat; and neither air speed nor clothing was considered. [Description provided by NIOSH]
• Subjects:
  Decision Making Energy Metabolism Environmental Monitoring Health Care Facilities Workforce And Services Heat Stress Disorders Hot Temperature Humidity Occupational Health Risk Assessment Safety Temperature

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• Keywords:
  Adjusted Temperature Air-temperature Analytical-instruments Analytical-processes Author Keywords: Heat Stress Biological-monitoring Decision-making Exposure-assessment Exposure-levels Heat Heat-exposure Heat-stress Heat Index Medical-monitoring Medical-screening Metabolic-rate Radiant-energy Relative-humidity Risk-analysis Temperature-effects Time-weighted-average-exposure WBGT Wet-bulb-thermometers

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• ISSN:
  1545-9624
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Florida ; OSHA Region 4
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  323-333
• Volume:
  12
• Issue:
  5
• NIOSHTIC Number:
  nn:20045579
• Citation:
  J Occup Environ Hyg 2015 May; 12(5):323-333
• Contact Point Address:
  Thomas E. Bernard, College of Public Health, University of South Florida, Tampa FL 33612-3805
• Email:
  tbernard@health.usf.edu
• Federal Fiscal Year:
  2015
• Performing Organization:
  Sunshine Education and Research Center, University of South Florida
• Peer Reviewed:
  True
• Start Date:
  20050701
• Source Full Name:
  Journal of Occupational and Environmental Hygiene
• End Date:
  20290630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:4df2bfba5ec7d621fe7db2007e1d0c8670dd81f69226fdd506db5542d6780e25a41236a80a6f55276588e637c3b7139c29c300d02472a2709d0101f29bc40647
• Download URL:
  https://stacks.cdc.gov/view/cdc/200951/cdc_200951_DS1.pdf
• File Type:
  [PDF - 248.08 KB ]